When a visual field is presented for 40 or 80 msec and a subject is asked to judge the duration of the stimulus, judged duration is found to be less when the field is blank than when the field contains three letters, but is the same whether the three letters form a word or not. The perceived difference between "filled" and "blank" fields increases when the subject is required to memorize the presented letters. These data are consistent with a theory which assumes, inter alia, that a stimulus is analyzed by a visual information processor and a timer, that attention is shared between these processors, and that temporal judgments are based on the output of both processors.Most. if not all. theories about how temporal judgments are made contain the assumption that the perceived length of an interval depends on the "information" occurring during that interval. Because of this assumption. these theories depend on theories about how stimulus information is processed. stored. and retrieved within an organism. In the simplest case. where the stimulus consists. for example. of two lO-msec clicks separated by an interval. t , and the subject's task is to estimate t. the assumption has been made that the relevant stimulus information is the number of subjective pulses occurri ng during t ,